The Study On The Integrated Process Of Swine Wastewater Processing And The Optimizing For The Process Conditions

With the development of large-scale cultivation in our country, the environmental pollution results from the emission of large number of swine wastewater became increasingly worse. Swine wastewater, which charactered with high COD, high ratio of carbon and nitrogen, high SS and rich in N, P nutrition, in which the ratio of BOD5and COD is greater than0.4, therefore has strong biodegradability. However, the single treatment process at present cannot meet the requirement of pollution control for swine wastewater. In this study,we took the cultivation wastewater treatment project of pig export base, which belongs to Chu Ying farming Corporation lies in Xin zheng City as the research object. Holding the purpose of reducing the cost of the process and recycling the resource, we put forward a combined process that consists of improved UASB, Magnesium Ammonium Phosphate (MAP) precipitation, Membrane Bioreactor (MBR) and Subsurface Flow Constructed Wetland (SFCW) to process the swine wastewater. In the course of starting, debugging and running for each reactor, we finished the determination of the the optimum operating parameters of the combined process and the combinatorial optimization for integration process, besides, we had accounted the optimal infrastructure and operating costs and came up with the best combined process and its treatment results for the swine wastewater under different circumstances. The results showed that:(1) To recycle the ammonia in the swine wastewater, magnesium chloride and trisodium phosphate was chosen as supplementary of magnesium source and phosphorus source, respectively.On the purpose of recovering part of the ammonia in swine wastewater and adjusting the proportion of carbon,nitrogen and phosphorus in wastewater to make it applicable to the biological treatment process,we have determined the parameters of the process as below:The optimum molar ratio of magnesium,nitrogen and phosphorus is1.2:1:0.9, the content of ammonia in the recovered water was maintained at about170mg/L and the pH was maintained at about8.5.The recovered struvite has a content of4.1%for nitrogen,40.77%for phosphorus pentoxide and15.85%for magnesia,which is a high-quality slow-release fertilizer,solving the problem of linking up for MAP process and MBR process effectively and simplifying the operating procedures.(2) In the summer when the washing water for pigsty and domestic water for the breeders increased, the mixing sewage generated in the process of14breeders feeding280pigs,in which the concentration of ammonia is less than300mg/L,using "UASB+MBR+SFCW" combined process to process the swine wastewater has the advantage of low cost and good effect. However, it cannot meet the requirements for the work of large amount of wastewater, as well as high concentration. To meet the high requirements for handling capacity, the " UASB+MAP+MBR+SFCW " combined process can achieve good results. This combined process is suitable for the processing of swine wastewater generated by the cultivation that using dry desludging mothod. It took the advantage of large handling capacity, strong anti-load capacity and can recycle high-quality slow-release fertilizer compared with the "UASB+MBR+SFCW" process.